(1) Field of the Art
This invention concerns a seismosensitive device which is arranged to open a switch means upon tremor of the earth so as to prevent a heating apparatus or the equivalent from developing into an abnormal condition and more particularly relates to a seismoscope in which said switch means comprises a drop of mercury and an electrode means having its lower end immersed into the drop.
(2) Description of the Prior Art
In a seismosensitive device in which a drop or globule of mercury is incorporated as an inertia mass, since the globule itself serves as a movable contact, the device has the capability of reducing size and frictional loss compared with counterpart prior devices in which a snap-action contact mechanism such as a microswitch is employed to be off-actuated by means of inertia mass such as a solid ball, pendulum or the like when an earthquake occurs.
This makes us induce the following requirements to be taken into consideration. One is that the physical condition of the surface where the mercury globule is to be placed affects its moving characteristics to a significant degree. The other is that when a globule of mercury is reduced to below 1 g in weight, it ends to retain itself in substantially spherical configuration under the influence of surface tension and not to conform to the shape of the enclosure in which the drop is placed.